Methods and apparatuses for implantable medical device telemetry power management

ABSTRACT

An implantable medical device includes a radio-frequency (RF) telemetry circuit connected to an energy source through a power connection module to obtain power when a user initiates an RF telemetry session. After the session is completed, the power connection module shuts off the at least one portion of the RF telemetry circuit. Power-on examples include a wireless telemetry activation signal received by a low power radio receiver in the implantable device, a physical motion detected by an activity sensor therein, an activation of an inductive telemetry circuit therein, a magnetic field detected by a magnetic field detector therein, and/or a telemetry activation signal detected by a sensing circuit included therein. Power-off examples include a wireless termination signal received by the implantable device, a delay timeout after the session, and/or a signal received by an inductive telemetry circuit in the implantable device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.10/071,255, filed on Feb. 7, 2001, the specification of which isincorporated herein by reference.

This application is related to co-pending, commonly assigned Von Arx etal. U.S. patent application Ser. No. 10/025,223, entitled “A TELEMETRYDUTY CYCLE MANAGEMENT SYSTEM FOR AN IMPLANTABLE MEDICAL DEVICE,” filedDec. 19, 2001 and Von Arx et al. U.S. patent application Ser. No.10/025,183, entitled “AN IMPLANTABLE MEDICAL DEVICE WITH TWO OR MORETELEMETRY SYSTEMS,” filed Dec. 19, 2001, each of which is herebyincorporated by reference.

TECHNICAL FIELD

This document relates generally to implantable medical devices andparticularly, but not by way of limitation, to such a device includingpower management of a telemetry system allowing communication with anexternal device.

BACKGROUND

Medical devices are implanted in human bodies for monitoringphysiological conditions, diagnosing diseases, treating diseases, orrestoring functions of organs or tissues. Examples of such implantablemedical devices include cardiac rhythm management systems, neurologicalstimulators, neuromuscular stimulators, and drug delivery systems.Because such a device may be implanted in a patient for a long time, thesize and power consumption of the device are inherently constrained.Consequently, an implantable device may depend on an external system toperform certain functions. Communication between the implantable deviceand the external system is referred to as telemetry. Examples ofspecific telemetry functions include programming the implantable deviceto perform certain monitoring or therapeutic tasks, extracting anoperational status of the implantable device, transmitting real-timephysiological data acquired by the implantable device, and extractingphysiological data acquired by and stored in the implantable device.

One particular example of implantable medical devices is a cardiacrhythm management device implanted in a patient to treat irregular orother abnormal cardiac rhythms by delivering electrical pulses to thepatient's heart. Such rhythms result in diminished blood circulation.Implantable cardiac rhythm management devices include, among otherthings, pacemakers, also referred to as pacers. Pacers are often used totreat patients with bradyarrhythmias, that is, hearts that beat tooslowly or irregularly. Such pacers may coordinate atrial and ventricularcontractions to improve the heart's pumping efficiency. Implantablecardiac rhythm management devices also include devices providing cardiacresynchronization therapy (CRT), such as for patients with congestiveheart failure (CHF). CHF patients have deteriorated heart muscles thatdisplay less contractility and cause poorly synchronized heartcontraction patterns. By pacing multiple heart chambers or multiplesites within a single heart chamber, the CRT device restores a moresynchronized contraction of the weakened heart muscle, thus increasingthe heart's efficiency as a pump. Implantable cardiac management devicesalso include defibrillators that are capable of delivering higher energyelectrical stimuli to the heart. Such defibrillators may also includecardioverters, which synchronize the delivery of such stimuli toportions of sensed intrinsic heart activity signals. Defibrillators areoften used to treat patients with tachyarrhythmias, that is, hearts thatbeat too quickly. In addition to pacers, CRT devices, anddefibrillators, implantable cardiac rhythm management systems alsoinclude, among other things, pacer/defibrillators that combine thefunctions of pacers and defibrillators, drug delivery devices, and anyother implantable systems or devices for diagnosing or treating cardiacarrhythmias.

Typically, an implantable cardiac rhythm management device communicates,via telemetry, with an external device referred to as a programmer. Onetype of such telemetry is based on inductive coupling between twoclosely-placed coils using the mutual inductance between these coils.This type of telemetry is referred to as inductive telemetry ornear-field telemetry because the coils must typically be closelysituated for obtaining inductively coupled communication. One example ofsuch an inductive telemetry is discussed in Brockway et al., U.S. Pat.No. 4,562,841, entitled “PROGRAMMABLE MULTI-MODE CARDIAC PACEMAKER,”assigned to Cardiac Pacemakers, Inc., the disclosure of which isincorporated herein by reference in its entirety.

In one example, an implantable device includes a first coil and atelemetry circuit, both sealed in a metal housing (referred to as a“can”). The external programmer provides a second coil in a wand that iselectrically connected to the programmer. During device implantation, aphysician evaluates the patient's condition, such as by using theimplanted device to acquire real-time physiological data from thepatient and communicating the physiological data in real-time to theexternal programmer for processing and/or display. The physician mayalso program the implantable device, including selecting a pacing ordefibrillation therapy mode, and parameters required by that mode, basedon the patient's condition and needs. The data acquisition and deviceprogramming are both performed using the inductive telemetry. If thepatient's condition is stable after implantation, he or she needs noattention from the physician or other caregiver until a scheduledroutine follow-up. During a typical routine follow-up, the physicianreviews the patient's history with the implantable device, re-evaluatesthe patient's condition, and re-programs the implantable device ifnecessary.

One problem with inductive telemetry is its requirement that the twocoils are closely placed. This typically requires placing the wand onthe body surface over the implantable device. Because the wand iselectrically connected to the programmer using a cable, the inductivetelemetry limits the patient's mobility.

To improve communication range and patient mobility, a far-fieldradio-frequency (RF) telemetry may be used, in which an RF transceiverin the implantable device is used to communicate with an RF transceiverin the external programmer. With a far-field RF telemetry, the patientis typically free of any body surface attachment that limits mobility.However, RF telemetry may consume several thousand times more energythan inductive telemetry.

For these and other reasons, the present inventors have recognized anunmet need for long-range telemetry at reduced energy consumption fromthe implantable device.

SUMMARY

An implantable medical device includes a radio-frequency (RF) telemetrycircuit that includes a power switch through which the RF telemetrycircuit is connected to an energy source such as a battery. The powerswitch is closed to connect power from the energy source to the RFtelemetry circuit when a user initiates an RF telemetry session. Afterthe RF telemetry session is completed, the power switch is opened toshut off at least a portion of the RF telemetry circuit.

In one example, the RF telemetry circuit is powered on by sending atelemetry activation signal from the remote device to the implantabledevice. A physician or other caregiver operating the remote deviceinitiates an RF telemetry session. The power switch is closed when thetelemetry activation signal is detected by the implantable device.

In another example, the RF telemetry circuit is powered on by a physicalmovement sensed by an accelerometer and detected by the implantabledevice. A patient with the implantable device initiates an RF telemetrysession by tapping on the skin over the implantable device. The powerswitch is closed when the implantable device detects an accelerationresulted from the tapping.

In another example, the RF telemetry circuit is powered on by activatingan inductive telemetry circuit included in the implantable device. Aphysician or other caregiver operating an external programmer initiatesan inductive telemetry operation in order to initiate an RF telemetrysession. The power switch is closed when an inductive telemetry circuitin the implantable device is activated.

In another example, the RF telemetry circuit is powered on by a magneticfield detected by the implantable device. A physician or other caregiverwaves a magnet or a hand held device generating a magnetic field toinitiate an RF telemetry session. The power switch is closed when themagnetic filed exceeds a predetermined level and is detected by theimplantable device.

In another example, the RF telemetry circuit is powered on byintroducing a telemetry activation signal into the patient through asurface electrocardiography (ECG) recording system. A physician or othercaregiver operating the remote device including an ECG module initiatesan RF telemetry session. The power switch is closed when the telemetryactivation signal is detected by a biopotential sensing circuit in theimplantable device.

In another example, the RF telemetry circuit is powered on byintroducing a telemetry activation signal into a patient throughcontacts between the patient and an external device adopted fortelemetry activation. A patient initiates an RF telemetry session bycontacting the external device. The power switch is closed when thetelemetry activation signal is detected by a biopotential sensingcircuit in the implantable device.

In one example, the RF telemetry circuit is shut off when a terminationsignal sent from the remote device through the RF telemetry is receivedby the implantable device. A physician or other caregiver operating theremote device may issue the termination signal. Alternatively, thetermination signal may be sent when the remote device determines thatthe RF telemetry session is to be concluded. The power switch is openedwhen the implantable device receives the termination signal.

In another example, the RF telemetry circuit is shut off after apredetermined delay following an end of a data transmission session. Atimer is started when the data transmission stops. The power switch isopened at the end of the predetermined delay if the data transmissionhas not resumed.

In another example, the RF telemetry circuit is shut off by activatingan inductive telemetry circuit included in the implantable device. Aphysician or other caregiver operating an external programmer terminatesan RF telemetry session. The power switch is closed immediately afterthe inductive telemetry circuit in the implantable device is activated.

Depending on a patient's needs for care and type of implantable device,one or more of the power-on methods and one or more of the power-offmethods discussed in this document may be included in one implantabledevice. Using more than one method to connect/disconnect power from theenergy source to the RF telemetry circuit increases the reliability ofinitiating and terminating the RF telemetry session in a timely mannerto ensure patient safety and conserve energy and hence device longevity.Other aspects of the present systems, devices, and methods will becomeapparent upon reading the following Detailed Description and viewing thedrawings that form a part thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsdescribe substantially similar components throughout the several views.Like numerals having different letter suffixes represent differentinstances of substantially similar components. The drawings illustrategenerally, by way of example, but not by way of limitation, variousembodiments discussed in the present document.

FIG. 1 is a schematic illustration of an example of portions of animplantable system 100 and portions of an environment in which it isused.

FIG. 2 is a schematic/block diagram illustrating one example of portionsof a telemetry power management system for an implantable medicaldevice.

FIG. 3A is a schematic/block diagram illustrating one example ofportions of a telemetry power management system controlling power-on byusing a telemetry activation signal detector including a low power radioreceiver.

FIG. 3B is a schematic illustrating one example of the low power radioreceiver.

FIG. 4 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 3A.

FIG. 5 is a schematic/block diagram illustrating one example of portionsof a telemetry power management system controlling power-on by detectinga physical activity.

FIG. 6 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 5.

FIG. 7 is a schematic illustration of one example of portions of atelemetry power management system controlling power-on by activatinginductive telemetry.

FIG. 8 is a schematic/block diagram illustrating one example of portionsof a telemetry power management system corresponding to the example ofFIG. 7.

FIG. 9 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 8.

FIG. 10 is a schematic illustration of one example of portions of atelemetry power management system controlling power-on by creating amagnetic field near the implantable medical device.

FIG. 11 is a schematic/block diagram illustrating one example ofportions of a telemetry power management system corresponding to theexample of FIG. 10.

FIG. 12 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 11.

FIG. 13 is a schematic illustration of one example of portions of atelemetry power management system controlling power-on by introducing asignal through an electrocardiograph (ECG) system.

FIG. 14 is a circuit diagram illustrating one example of portions of thetelemetry power management system of FIG. 13.

FIG. 15 is a schematic illustration of another example of portions of atelemetry power management system controlling power-on by introducing asignal through an electrocardiograph (ECG) system.

FIG. 16 is a circuit diagram illustrating one example of portions of thetelemetry power management system of FIG. 15.

FIG. 17 is a schematic/block diagram illustrating one example ofportions of a telemetry power management system corresponding to theexamples of FIGS. 14 and 16.

FIG. 18 is a schematic/block diagram illustrating one example ofportions of a sensing amplifier.

FIG. 19 is a schematic/block diagram illustrating another example ofportions of a sensing amplifier.

FIG. 20 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 17.

FIG. 21 is a schematic illustration of one example of portions of atelemetry power management system controlling power-on by using anexternal telemetry activation device.

FIG. 22 is a schematic/block diagram illustrating one example ofportions of telemetry power management system corresponding to theexample of FIGS. 21.

FIG. 23 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 22.

FIG. 24 is a schematic/block diagram illustrating one example ofportions of a telemetry power management system controlling power-off bysending a command via RF telemetry.

FIG. 25 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 24.

FIG. 26 is a schematic/block diagram illustrating one example ofportions of a telemetry power management system controlling power-off byusing a timer.

FIG. 27 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 26.

FIG. 28 is a flow chart illustrating one example of a methodcorresponding to one example of a telemetry power management systemcontrolling power-off by using an inductive telemetry.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, and in which is shown, byway of illustration, specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that the embodiments may be combined, or that otherembodiments may be utilized and that structural, logical and electricalchanges may be made without departing from the scope of the presentinvention. The following detailed description is, therefore, not to betaken in a limiting sense, and the scope of the present invention isdefined by the appended claims and their equivalents.

This document discusses, among other things, power management oftelemetry circuit in an implantable medical device. The present methodsand apparatuses will be described in applications involving implantablecardiac rhythm management systems such as pacemakers, CRT devices,cardioverter/defibrillators, and pacer/defibrillators. However, it isunderstood that the present methods and apparatuses may be employed inother types of implantable medical devices, including, but not beinglimited to, neurological stimulators, neuromuscular stimulators, drugdelivery systems, and various types of physiological signal monitoringdevices.

FIG. 1 is a schematic illustration of an example of portions of amedical system 100 and portions of an environment in which it is used.In this example, system 100 is a cardiac rhythm management systemincluding, among other things, an implanted device 110 and a remoteexternal device 140. Implanted device 110 is implanted within apatient's body 101 and coupled to the patient's heart 102 by a leadsystem 105. Examples of implanted device 110 include pacemakers, CRTdevices, cardioverter/defibrillators, and pacer/defibrillators. Remoteexternal device 140 provides a user interface for system 100. The userinterface allows a physician or other caregiver to interact withimplanted device 110 through a wireless telemetry link. In the exampleof FIG. 1, the wireless telemetry link is a radio-frequency (RF)telemetry link 150 supported by RF transceivers residing in implanteddevice 110 and external device 140. RF telemetry link 150 provides forbi-directional data communication between implanted device 110 andremote device 140.

In one example, RF telemetry link 150 provides for data transmissionfrom implanted device 110 to remote device 140. This may include, forexample, transmitting real-time physiological data acquired by implanteddevice 110, extracting physiological data acquired by and stored inimplanted device 110, extracting therapy history data stored inimplanted device 110, and extracting data indicating an operationalstatus of implanted device 110 (e.g., battery status and leadimpedance). In a further example, RF telemetry link 150 transmits datafrom remote device 140 to implanted device 110. This may include, forexample, programming implanted device 110 to acquire physiological data,programming implanted device 110 to perform at least one self-diagnostictest (such as for a device operational status), and programmingimplanted device 110 to deliver at least one therapy.

In one example, RF telemetry link 150 is a far-field telemetry link. Afar-field, also referred to as the Fraunhofer zone, refers to the zonein which a component of an electromagnetic field produced by thetransmitting electromagnetic radiation source decays substantiallyproportionally to 1/r, where r is the distance between an observationpoint and the radiation source. Accordingly, far-field refers to thezone outside the boundary of r=λ/2π, where λ is the wavelength of thetransmitted electromagnetic energy. In one example, a communicationrange of RF telemetry link 150 (a distance over which data is capable ofbeing wirelessly communicated) is at least six feet but can be as longas allowed by the particular communication technology. Unlike aninductive telemetry link using a wand placed near implanted device 110,typically attached to the patient, and electrically connected to remoteexternal device 140 with a cable, using RF telemetry link 150 frees thepatient from any physical restraints caused by the wand and the cable.On the other hand, the power consumed by implanted device 110 to supporta far-field RF telemetry can be as high as ten thousand times that ofinductive telemetry. To reduce the energy consumption of implanteddevice 110, the present inventors have recognized the need for powermanagement to reduce the energy drawn from implanted device 110 tosupport the RF telemetry link 150.

FIG. 2 is a schematic/block diagram illustrating one example of portionsof a telemetry power management system for implantable medical device.In this example, implantable medical system 100 includes implanteddevice 110, external remote device 140, and RF telemetry link 150.Remote device 140 includes a remote RF telemetry circuit 242 and aremote antenna 243. Implanted device 110 includes an energy source 211,an implanted RF telemetry circuit 212, an implanted antenna 213, and aswitch controller 214. RF telemetry circuits 212 and 242, throughantenna 213 and 243, respectively, communicate using RF telemetry link150. A power switch 215, when closed, connects implanted RF telemetrycircuit 212 to energy source 211 to draw energy therefrom. In manyapplications of system 100, data is being transmitted for a smallfraction of the time when implanted device 110 is in use. Therefore, RFtelemetry circuit 212 only needs to be powered during a datatransmission (and for a short preceding power-up period). In thisexample, an output of switch controller 214 drives power switch 215.Switch controller 214 closes power switch 215 when implantable RFtelemetry circuit 212 is powered to support the data transmission overRF telemetry link 150 and opens power switch 215 shortly after the datatransmission is completed. This document presents several specificillustrative examples of controlling the power-on and power-off statusof RF telemetry circuit 212, such as by closing and opening power switch215, respectively. The examples can be combined in any way.

In this document, “power switch” refers generally to any powerconnection module, not limited to an on/off switch, that, in one examplecontrols an activation (or power-on) and deactivation (or power-off) ofthe RF telemetry. In one example, the RF telemetry circuit is poweredon, or activated, when it enters an energization state that enables itto perform its intended telemetry function. In another example, the RFtelemetry circuit is powered off, or deactivated, when it enters anotherenergizaton state that maintains the circuit off or in a “sleep” or“barely awake” mode to conserve energy. In one example, the power switchconnects/disconnects power from the energy source to one or moreportions of the RF telemetry circuit.

In one example, power switch 215 connects/disconnects power from energysource 211 to portions of RF telemetry circuit 212. After the telemetrysession is terminated, power switch 215 disconnects power from theportions of RF telemetry circuit 212 but maintains power connection toother portions of RF telemetry circuit 212, such that RF telemetrycircuit 212 may be activated quickly when a new telemetry session isinitiated.

Example of Power-On by Using a Low-Power Radio Receiver

FIG. 3A is a schematic/block diagram illustrating one example ofportions of a telemetry power management system controlling power-on ofat least a portion of the telemetry. In this example, power switch 215is closed to connect power from energy source 211 to implanted RFtelemetry circuit 212 when implanted device 110 receives an radiosignal. Remote device 140 includes a telemetry activation signalgenerator 346 coupled to remote antenna 243. Switch controller 214includes a telemetry activation signal detector 316 coupled to implantedantenna 213. Telemetry activation signal detector 316 includes a lowpower radio receiver 317. Low power radio receiver 317 is always awaketo respond to telemetry activation signals. To initiate a datatransmission over RF telemetry link 150, a telemetry activation signalis generated by telemetry activation signal generator 346 and emittedthrough remote antenna 243. Upon receiving the telemetry activationsignal through implanted antenna 213, telemetry activation signaldetector 316 closes power switch 215 to operate implanted RF telemetrycircuit 212. The telemetry activation signal is a radio signal having anamplitude and frequency in compliance with applicable governmentregulations. In one example, the telemetry activation signal is ahigh-power RF burst signal.

FIG. 3B is a schematic illustrating one example of low power radioreceiver 317. Low power radio receiver includes a tank circuit 318, adiode 319, a low-pass filter 320, and a low-power comparator 321. Tankcircuit, coupled to antenna 213 to receive a signal including thetelemetry activation signal, includes an inductor and a capacitor toform a high-Q resonant circuit that obtains a gain passively. Diode 319is a non-linear element for rectifying the received signal. Low passfilter 320 includes a resistor and a capacitor to detect an envelope ofthe rectified signal. Low power comparator generates an outputindicating a detection of the telemetry activation signal when at leasta portion of the envelope exceed a predetermined detection threshold. Inone example, low power radio receiver operates with a supply current ofapproximately 100 nA -500 nA.

FIG. 4 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 3A. At 400, an RF telemetry sessionis initiated at remote device 140. In one example, the RF telemetrysession is initiated by a physician or other caregiver. In anotherexample, the RF telemetry session is initiated automatically by remotedevice 140, e.g., occasionally or periodically. In one example, the RFtelemetry session is initiated for a regular check-up of a status of thedevice and conditions of the patient in whom the device is implanted. Inone example, the RF telemetry session is initiated in response to aphone from a person, such as a caregiver or the patient, regarding acondition of the patient that needs immediate attention. At 410, remotedevice 140 sends out a telemetry activation signal. The telemetryactivation signal is a radio signal having an amplitude and frequency incompliance with applicable government regulations. In one example, thetelemetry activation signal is an RF burst. In a further example, the RFburst has a duration of up to five milliseconds and an amplitudesufficient to be received by implanted RF telemetry circuit 212 up to apredetermined distance from remote device 140. Typically, the RF burstreceived at implanted RF telemetry circuit 212 has an amplitude of atleast 1 mV. In one example, the RF burst amplitude used is determinedbased on an environmental noise and a signal-to-noise ratio that ensuresreliable detection by diode detector 317. In one example, remote devicesends a digital key that follows the telemetry activation signal. Thedigital key is a coded signal identifying a particular implantabledevice 110. If the telemetry activation signal is received by at leastone implanted device 110 within the predetermined distance from remotedevice 140, power switch 215 in that particular implanted device 110 isclosed at 430 for connecting RF telemetry circuit 212 and energy source211 of that implanted device 110. At 440, telemetry device is activatedto perform RF telemetry functions. At 450, if the particular implanteddevice 110 receives the digital key matching its identification code, itsends a responsive signal to remote device 140. In one example,implanted device 110 is prevented from sending out any signal after anend of the RF telemetry session until a matched digital key is receivedat the beginning of a new RF telemetry session. The reception of thisresponsive signal by remote device 140 indicates that RF telemetry hasbeen successfully established, i.e., RF telemetry link 150 is ready forbidirectional data transmission. If the identification code fails tomatch the identification of the particular implanted device 110, itspower switch 215 is opened at 455, and remote device 140 repeats theprocess at 410 after a predetermined delay 415. After the RF telemetryis established at 450, data is transmitted from remote device 140 toimplanted device 110 and/or from implanted device 110 to remote device140 at 460. The RF telemetry enters an idle state following an end ofthe RF telemetry session, when RF telemetry circuit 212 is powered butno data is being transmitted between implanted device 110 and remotedevice 140. After the RF telemetry enters an idle state, power switch215 is opened at 470 to disconnect power to at least a portion of RFtelemetry circuit 212. Examples of methods and apparatus controlling theopening of power switch 215 are described later in this document. At480, remote device 140 indicates whether the telemetry session wassuccessful, such as by logging or displaying a message.

Example of Power-On by Physical Motion

FIG. 5 is a schematic/block diagram illustrating another example ofportions of a telemetry power management system controlling power-on ofat least a portion of the telemetry. In this example, power switch 215is closed to connect power from energy source 211 to RF telemetrycircuit 212 when a patient activity (e.g., a body motion) of apredetermined magnitude, duration, and/or pattern is detected. In thisexample, switch controller 214 includes accelerometer 520 and a sensorsignal processing circuit 521. Accelerometer 520 senses acceleration ofimplanted device 110, resulted from body motion of the patient. In oneexample, sensor processing circuit 521 includes an amplifier and afilter to condition the activity signal sensed by accelerometer 520 anda comparator to compare the conditioned acceleration signal to apredetermined acceleration threshold. If the conditioned accelerationsignal exceeds the predetermined acceleration threshold, sensorprocessing circuit 521 outputs a signal to close power switch 215. In anadditional example, sensor processing circuit 521 further includes apattern recognition module to detect a predetermined pattern ofacceleration. One example of such pattern of acceleration includes threemomentary acceleration impulses that are about one second apart fromeach other and all exceed the predetermined acceleration threshold.

FIG. 6 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 5. At 600, a physical movement ofthe patient in whom implanted device 110 is implanted initiates an RFtelemetry session. In one example, the patient initiates an RF telemetrysession to inform or alert a physician or caregiver of his recent orpresent condition. To initiate the telemetry operation at 610, thepatient taps on his/her skin over implanted device 110. The movementresulted from the tapping is sensed by accelerometer 520. If the tappingresults in an acceleration that exceeds a predetermined thresholdacceleration level at 620, sensor processing circuit 521 outputs asignal that closes power switch 215 at 625. If the acceleration is belowthe threshold, the tapping does not initiate an RF telemetry session. Inanother example, in addition to requiring that acceleration exceeds apredetermined threshold acceleration level, the tapping activity mustalso exhibit a predetermined pattern, and sensor processing circuit 521outputs a signal to close power switch 215 at 625. One suitablepredetermined pattern of movement results from tapping on the skin overthe device three times in approximately one-second intervals. At 630,just after switch 215 is closed, RF telemetry circuit 212 is activatedand ready for bi-directional communication with remote device 140 via RFtelemetry link 150. In one example, RF telemetry circuit 212 sends out asignal to remote device 140 to establish RF telemetry. If the signal isreceived by remote device 140, and remote device 140 is available forcommunication, remote device 140 sends a response signal back toimplanted device 110, and the RF telemetry is established at 640. If theRF telemetry cannot be established, because, for example, there is noavailable remote device 140 within the RF telemetry range, implanted RFtelemetry circuit 212 will repeat 630 after a predetermined delay 645.In one example, delay 645 is a programmable constant. A suitable rangeof this constant is 0.5 to 2 seconds. In another example, delay 645 is afunction of the number of unsuccessful attempts to establish the RFtelemetry. This function represents a particular sequence of successiveattempts to establish the RF telemetry. For example, if the firstattempt fails, the next five attempts may be made in about one-minuteintervals. If the RF telemetry is still not established, furtherattempts may be made in about 30-minute intervals. Other examples ofsuccessive attempts may include a time interval between consecutiveattempts that increases linearly or exponentially. In another example,remote device 140 occasionally or periodically sends a signal includinga digital key identifying a particular implantable device 110. Inresponse to receiving this signal, RF telemetry circuit 212 sends out asignal to remote device 140 to establish RF telemetry at 640. In thisexample, implantable device 110 is prevented from starting RF telemetrycommunications without an authorization from remote device 140. Thus,implant device 110 need not make repeated attempts to establish RFtelemetry, thereby saving energy. This also prevents the situation inwhich multiple implantable devices compete to establish RF telemetrywith one remote device 140 by giving remote device 140 the control overwhich particular implantable device 110 to communicate with.Furthermore, preventing implantable device 110 from initiating signaltransmission ensures that implantable device 110 does not accidentallysent RF signals in violation of applicable government regulations whenthe patient travels to a different country. After the RF telemetry isestablished at 640, data is transmitted from remote device 140 toimplanted device 110 and/or from implanted device 110 to remote device140 at 650. After the RF telemetry enters an idle state, power switch215 is opened at 660 to disconnect power from energy source 211 to atleast a portion of RF telemetry circuit 212. Examples of methods andapparatus controlling the opening of power switch 215 are describedlater in this document. At 670, remote device 140 indicates whether thetelemetry session was successful, such as by logging or displaying amessage.

Example of Power-On by Activating Inductive Telemetry

FIG. 7 is a schematic illustration of another example of portions of atelemetry power management system controlling power-on of at least aportion of the telemetry. In this example, system 100 includes anadditional remote device, such as an external programmer 745. Externalprogrammer 745 and implanted device 110 include respective circuitsproviding an inductive telemetry link 755. Inductive telemetry link 755uses mutual inductance between two closely placed coils, one atimplanted device 110 and the other carried by a wand 746. Wand 746 iscoupled to the external programmer 745 via a cable. When wand 746 is inplace to form an adequate mutual inductance between the coils, externalprogrammer 745 sends implanted device 110 a synchronization signal toestablish inductive telemetry link 755. The establishment of inductivetelemetry link 755 initiates the process of establishing the RFtelemetry session. This process includes that the implanted device 110powers up its RF telemetry circuit and sends a signal to remote device140. The RF telemetry is established when implanted device 110 receivesa response signal from remote device 140. In one example, remote device140 and programmer 745 are physically integrated into one single device.

FIG. 8 is a schematic/block diagram illustrating one example of portionsof a telemetry power management system corresponding to the example ofFIG. 7. In this example, system 100 includes implanted device 110,remote device 140, and external programmer 745. In one example, remotedevice 140 and programmer 745 are physically integrated into one singledevice. Implanted device 110 communicates with remote device 140 via RFtelemetry link 150, or with external programmer 745 via inductivetelemetry link 755. External programmer 745 includes an externalinductive telemetry circuit 847. Switch controller 214 in implanteddevice 110 includes an implantable inductive telemetry circuit 828including an output that controls power switch 215. Inductive telemetrylink 755 uses mutual inductance between coil 829 and another coil inwand 746. The coil in wand 746 is electrically connected to externalinductive telemetry circuit 847. Switch 215 is closed to connect powerfrom energy source 211 to RF telemetry circuit 212 after implantedinductive telemetry circuit 828 becomes active, i.e., after inductivetelemetry link 755 is ready for bidirectional data communication. Theinductive telemetry need not remain active after the RF telemetry isestablished.

FIG. 9 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 8. At 900, a physician or othercaregiver initiates an RF telemetry session by placing or waving wand746 near implanted device 110. In one example, the RF telemetry sessionis initiated for evaluating a patient's condition, and RF telemetryprovides patient mobility after wand 746 is removed. In another example,the RF telemetry session is initiated just before implanted device 110is implanted in a patient. The RF telemetry avoids bringing wand 746into the sterile field of the operation. At 910, inductive telemetrylink 755 is established. External programmer 745 indicates whetherinductive telemetry link 755 was successfully established. Ifestablishment of inductive telemetry link 755 was unsuccessful, thephysician or other caregiver adjusts the position of wand 746 until suchsuccess is obtained. In one example, external programmer 745 sends asynchronization signal to implanted device 110. Upon receiving thesynchronization signal, implanted inductive telemetry circuit 828 sendsa return signal back to external programmer 745, and inductive link 755is established at 910 when external inductive telemetry circuit 847receives the return signal. At 920, power switch 215 is closed toconnect power from energy source 211 to implanted RF telemetry circuit212. At 930, RF telemetry circuit 212 is activated and ready forbi-directional communication with remote device 140 via RF telemetrylink 150. In one example, implanted RF telemetry circuit 212 sends asignal to remote device 140. If the signal is received by remote device140, and remote device 140 is not busy with ongoing telemetry with otherimplantable device(s), remote device 140 sends a responsive signal backto implanted device 110, and the RF telemetry is established at 940. Ifthe RF telemetry cannot be established at 940, because, for example,there is no available remote device 140 within the RF telemetry range,RF telemetry circuit 212 will repeat 930 after a delay 945. In oneexample, delay 945 is a programmed constant. In another example, delay945 is a function of the number of unsuccessful attempts to establishthe RF telemetry. This function represents a particular sequence ofsuccessive attempts to establish the RF telemetry. In another example,remote device 140 periodically sends a signal including a digital keyidentifying a particular implantable device 110. Only upon receivingthis signal, RF telemetry circuit 212 sends out a signal to remotedevice 140 to establish RF telemetry at 940. At 950, external programmer745 indicates whether RF telemetry link 150 has been established. In oneexample, the physician or caregiver may then remove wand 746 from nearimplanted device 110 at 950, leaving the patient free of cableattachment. In another example, the physician or caregiver must removewand 746 from near implanted device 110 at 950 before the RF telemetrycan be established because the inductive telemetry is given priorityover the RF telemetry. At 960, data is transmitted from remote device140 to implanted device 110 and/or from implanted device 110 to remotedevice 140. After the RF telemetry enters an idle state, power switch215 is opened at 970 to disconnect power from energy source 211 to atleast a portion of RF telemetry circuit 212. Examples of methods andapparatuses controlling the opening of power switch 215 are describedlater in this document. At 980, remote device 140 indicates whether thetelemetry session was successful, such as by logging or displaying amessage.

Example of Power-On by Magnetic Field

FIG. 10 is a schematic illustration of another example of portions of atelemetry power management system controlling power-on of at least aportion of the telemetry. In this example, system 100 includes amagnetic field provider 1048. The RF telemetry session is initiated whenimplanted device 110 detects a magnet field. In one example, magneticfield provider 1048 includes a permanent magnet. In another example,magnetic field provider 1048 includes a hand-held, battery-poweredmagnetic field provider, such as a wireless, battery operated inductivewand. In another example, magnetic field provider 1048 is an externalprogrammer including an inductive telemetry circuit or other circuit orother device generating a magnetic field.

FIG. 11 is a schematic/block diagram illustrating one example ofportions of a telemetry power management system corresponding to theexample of FIG. 10. In this example, system 100 includes implanteddevice 110, remote device 140, and magnetic field provider 1048. Switchcontroller 214 in implanted device 110 includes a reed switch or othermagnetic field detector 1130 that controls power switch 215. Powerswitch 215 is closed to connect power from energy source 211 to RFtelemetry circuit 212 when a magnetic field is detected by magneticfield detector 1130 exceeds a threshold.

FIG. 12 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 11. At 1200, a physician or othercaregiver initiates an RF telemetry session by momentarily wavingmagnetic field provider 1048 near implanted device 110. In one example,the RF telemetry session allows evaluation of a patient's conditionwhile providing patient mobility. At 1210, the magnetic field frommagnetic field provider 1048 is detected by magnetic field detector 1130when the field strength exceeds a threshold level. In response, at 1220,power switch 215 is closed to connect power from energy source 211 toimplanted RF telemetry circuit 212. At 1230, RF telemetry circuit 212 isactivated and ready for bi-directional communication with remote device140 via RF telemetry link 150. In one example, implanted RF telemetrycircuit 212 sends a signal to remote device 140. If the signal isreceived by remote device 140, and remote device 140 is not busycommunicating with other implantable device(s), remote device 140 sendsa responsive signal back to implanted device 110, establishing RFtelemetry at 1240. If the RF telemetry cannot be established at 1240,because, for example, there is no available remote device 140 within theRF telemetry range, RF telemetry circuit 212 will repeat 1230 after adelay 1245. In one example, delay 1245 is a programmed constant. Inanother example, delay 1245 is a function of the number of unsuccessfulattempts to establish the RF telemetry. This function represents aparticular sequence of successive attempts to establish the RFtelemetry. In another example, remote device 140 periodically sends asignal including a digital key identifying a particular implantabledevice 110. Only upon receiving this signal, RF telemetry circuit 212sends out a signal to remote device 140 to establish RF telemetry at1240. At 1250, data is transmitted from remote device 140 to implanteddevice 110 and/or from implanted device 110 to remote device 140. Afterthe RF telemetry enters an idle state, power switch 215 is opened at1260 to disconnect power from energy source 211 to at least a portion ofRF telemetry circuit 212. Examples of methods and apparatus controllingthe opening of power switch 215 are described later in this document. At1270, remote device 140 indicates whether the telemetry session wassuccessful, such as by logging or displaying a message.

Example of Power-On by Using Signal Introduced via Surface ECGElectrodes

FIG. 13 is a schematic illustration of another example of portions of atelemetry power management system controlling power-on of at least aportion of the telemetry by using an electrocardiograph (ECG) monitoringor recording system. In this example, remote device 140 includes an ECGmonitoring or recording module 1360. In one example, ECG module 1360 isused for assessing the behavior of implanted device 110 by observing thecardiac signals, such as through surface electrodes 1361A-D attached toa patient's skin. Once electrodes 1361A-D are electrically coupled toECG module 1360, a low-amplitude electrical current signal is sent tothe body from remote device 140, through two or more of electrodes 1361.This current signal is sensed by implanted device 110 as a telemetrypower-on signal. In one example, the low-amplitude electrical currentsignal includes an encoded command that can be easily distinguished fromnoise that may be present on electrodes 1361. Once RF telemetry link 150has been established, electrodes 1361 need not remain attached duringthe subsequent telemetry session.

FIG. 14 is a circuit diagram illustrating one example of portions of thetelemetry power management system of FIG. 13. In this example, ECGmodule 1360 is coupled to electrodes 1361, including three inputelectrodes 1361B-D and one right-leg negative feedback electrode 1351A.Right-leg negative feedback is a technique known in the art of ECGmonitoring or recording for reducing noise pickup due to a common-modevoltage on electrodes 1361B-D while increasing patient safety. ECGmodule 1360 includes a telemetry activation signal generator 1465 and asignal summing circuit 1466. In one example, a physician or othercaregiver initiates an RF telemetry session by providing an input at auser interface 1467. This input causes signal generator 1465 to issue atelemetry activation signal. In another example, signal generator 1465automatically issues a telemetry activation signal upon a predeterminedevent. This signal is summed into the negative feedback circuit andintroduced into the patient's body via electrode 1361A. In one example,the telemetry activation signal has a frequency much greater than 150Hz. This allows the telemetry activation signal to be filtered out fromthe monitored ECG signal sensed by electrodes 1361B-D.

FIG. 15 is a schematic illustration of another example of portions of atelemetry power management system controlling power-on of at least aportion of the telemetry by using an electrocardiograph (ECG) system. Inthis example, ECG module 1360 is used for assessing the behavior ofimplanted device 110 by observing the cardiac signals through two inputelectrodes 1361C-D attached to the body surface. At least a portion ofthe telemetry circuit in implanted device 110 is powered on in responseto a telemetry activation current signal injected into the body viaelectrodes 1361C-D.

FIG. 16 is a circuit diagram illustrating one example of portions of thetelemetry power management system of FIG. 15. In this example, ECGmodule 1360 is configured to operate using input electrodes 1361B-D,without right-leg negative feedback electrode 1351A. One of inputelectrodes 1361C and 1361D is used as an output for telemetry activationsignal generator 1465, such as by using a switch 1667. In the exampleshown in FIG. 16, a physician or other caregiver initiates an RFtelemetry session by providing an input to user interface 1467. Thisinput causes remote device 140 to inject telemetry activation signal viainput electrode 1361C.

FIG. 17 is a schematic/block diagram illustrating one example ofportions of system 100 corresponding in the examples of FIGS. 14 and 16.In this example, remote device 140 includes ECG module 1360, which iscoupled to electrodes 1361 attached to the patient. Electrodes 1361include four electrodes, 1361A-D, or alternatively, two electrodes,1361C-D, as respectively discussed above for FIGS. 14 and 16. Switchcontroller 214 includes a sensing amplifier 1731 and detector 1732. Inone example, in addition to sensing the telemetry activation signal,sensing amplifier 1731 is also used to sense a physiological signal.Examples of the sensed physiological signal include a cardiac signal, arespiration signal, and an acceleration signal. In one example, sensingamplifier 1731 is used to sense cardiac signals via electrodes 1733A and1733B. Electrodes 1733A-B are both electrically coupled to sensingamplifier 1731, such as through lead wires. In one example, electrodes1733A-B are disposed in close proximity to each other in or about aheart chamber. This is referred to as bipolar sensing. In an alternativeexample, electrode 1733A is disposed in or about a heart chamber, andelectrode 1733B is located at or near a metal housing of implanteddevice 110 that houses switch controller 214, energy source 211, andimplanted RF telemetry circuit 212. This is referred to as unipolarsensing. Sensing amplifier 1731 typically includes an amplifier and afilter. Detector 1732 includes a comparator having one input coupled tothe output of the sensing amplifier 1731, another input representativeof a predetermined comparison threshold, and an output indicatingwhether the signal sensed via electrodes 1733A-B exceeds the threshold.The output of detector 1732 is coupled to power switch 215 to closepower switch 215 when the telemetry activation signal sensed throughelectrodes 1733A-B exceeds the threshold. This, in turn, connects powerfrom energy source 211 to implanted RF telemetry circuit 212. In oneexample, detector 1732 further includes a binary code detector thatdetects a digital key, also sensed via electrodes 1733A-B. In oneexample, use of the digital key provides added noise immunity. Inanother example, the digital key also identifies a particularimplantable device 110 with which RF telemetry link 150 is to beestablished. Power switch 215 is closed when the telemetry activationsignal sensed through electrodes 1733A-B exceeds the threshold and amatching digital key is detected.

FIG. 18 is a schematic/block diagram illustrating one example ofportions of sensing amplifier 1731. In this example, amplifier 1834A isa low-frequency amplifier used to amplify the physiological signal.Amplifier 1834B is a high-frequency amplifier used to amplify thetelemetry activation signal. A filter 1835A attenuates signals that arenot at the physiological signal frequency. This configuration issuitable when a telemetry activation signal has a frequency that issignificantly different from the physiological signal frequency,avoiding the use of a wideband amplifier that may expose implantabledevice 110 to a wide range of noises. In one example, the physiologicalsignal is a cardiac signal, and filter 1835A includes a bandpass filterhaving a bandwidth of 150 Hz. Filter 1835B passes the telemetryactivation signal to detector 1732, and attenuates signals at otherfrequencies. This example uses a telemetry activation signal frequencythat is different, and therefore distinguishable, from that of thecardiac or other physiological signal.

FIG. 19 is a schematic/block diagram illustrating another example ofportions of sensing amplifier 173 1. In this example, sensing amplifier1731 includes a shared amplifier 1834A and two filters 1835A-B, bothcoupled to the output of amplifier 1834A. This configuration isalternative implementation to that of FIG. 18, eliminating components,however, the implementation of FIG. 18 allows more design flexibility inthe signal processing. In one example, the physiological signal sensedduring particular time periods and the telemetry activation signal issensed during other times. For example, a respiration signal ismonitored by periodically sensing body impedance. A telemetry activationsignal is injected into the body when the body impedance is not beingsensed.

FIG. 20 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 17. At 2000, a physician or othercaregiver initiates an RF telemetry session by providing input at a userinterface. In response, a telemetry activation signal is introduced intoa patient's body through ECG electrodes 1361. The telemetry activationsignal is a short-duration electrical current signal flowing into thebody when a switch in remote device 140 is momentarily closed. In oneexample, the telemetry activation signal includes a digital keyidentifying a particular implantable device 110 with which RF telemetrylink 150 is to be established. In one example, the RF telemetry sessionis initiated for an evaluation of a patient's conditions. At 2010, thetelemetry activation signal is detected by implanted device 110. Inresponse, at 2020, power switch 215 is closed to connect power fromenergy source 211 to implanted RF telemetry circuit 212. At 2030, RFtelemetry circuit 212 is activated and ready for bi-directionalcommunication with remote device 140 via RF telemetry link 150. In oneexample, implanted RF telemetry circuit 212 sends a signal to remotedevice 140. If the signal is received by remote device 140, and remotedevice 140 is not busy communicating with other implantable device(s),remote device 140 sends a responsive signal back to implanted device110, and the RF telemetry is established. If, at 2040, the RF telemetryis not established, because of excessive environmental noises or otherreasons, RF telemetry circuit 212 will repeat 2030 after a delay 2045.In one example, delay 2045 is a programmed constant. In another example,delay 2045 is a function of the number of failed attempts to establishthe RF telemetry. This function represents a particular sequence ofsuccessive attempts to establish the RF telemetry. In another example,remote device 140 periodically sends a signal including a digital keyidentifying a particular implantable device 110. Only upon receivingthis signal, RF telemetry circuit 212 sends out a signal to remotedevice 140 to establish RF telemetry at 2040. At 2050, remote device 140indicates that RF telemetry link 150 has been established. The physicianor caregiver may remove ECG electrodes 1361 so that the patient'smobility is no longer limited by their connecting cable. At 2060, datais transmitted from remote device 140 to implanted device 110 and/orfrom implanted device 110 to remote device 140. In an idle state, afterthe data transmission is complete, power switch 215 is opened at 2070.This disconnects power from energy source 211 to at least a portion ofRF telemetry circuit 212. Examples of methods and apparatus controllingthe opening of power switch 215 are described later in this document. At2080, remote device 140 indicates whether the telemetry session wassuccessful, such as by logging or displaying a message.

Example of Power-On by Momentary Contacting An External Device

FIG. 21 is a schematic illustration of another example of portions of atelemetry power management system controlling power-on of at least aportion of the telemetry by using an external telemetry activationdevice. In this example, system 100 includes a telemetry activationdevice 2170 that introduces a telemetry activation signal into apatient's body to be received by implanted device 110 for activatingtelemetry. In one example, the telemetry activation signal includes anencoded command that is distinguishable from noise that may be presenton electrodes 2171. In one example, device 2170 is dedicated totelemetry activation. In another example, device 2170 is a monitoringdevice, or a therapy device, or any medical device or non-medical deviceincorporating a telemetry activation system. In one example, device 2170includes a user input and/or output interface such as to accept commandsand display telemetry activity or other status information regardingimplanted device 110. Telemetry activation device 2170 includes a pairof conductive structures 2171 for contact with the patient. A smallelectrical current flows into the patient's body when the patientcontacts both conductive structures. In the example of FIG. 21, theconductive structures include a pair of conductive joysticks. Thepatient holds one joystick in each hand to initiate an RF telemetrysession for data transmission between implanted device 110 and remotedevice 140. In an alternative example, conductive structure 2171includes two conductive patches incorporated onto a bar, a handle, orany portion of the housing of telemetry activation device 2170. In oneexample, the patient initiates telemetry sessions periodically totransfer acquired physiological data and/or therapy history to aphysician or other caregiver. In another example, the patient initiatesa telemetry session when attention of the physician or other caregiveris needed.

FIG. 22 is a schematic/block diagram illustrating one example ofportions of telemetry power management system corresponding to theexample of FIG. 21. In this example, system 100 includes a telemetryactivation device 2170 having conductive structures 2171. Switchcontroller 214 includes sensing amplifier 1731 and detector 1732. In oneexample, sensing amplifier 1731 is also used to sense a physiologicalsignal via electrodes 1733A-B that are electrically coupled to sensingamplifier 1731. In one example, the sensed physiological signal is acardiac signal. Electrodes 1733A-B are configured for either bipolarsensing or unipolar sensing. Power switch 215 is closed to connect powerfrom energy source 211 to implanted RF telemetry circuit 212 in responseto the telemetry activation signal being sensed by sensing amplifier1731 and detected by detector 1732.

FIG. 23 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 22. At 2300, a user initiates an RFtelemetry session as scheduled or needed. In one example, the user is apatient. In another example, the user is a physician or other caregiverwho is supervising or examining the patient. At 2310, the user selectsan operation. In the example of FIG. 23, the user may elect to transferdata from implanted device 110 to remote device 140 immediately or aftera delay. If the user elects to transfer data after a delay, then at2315, telemetry activation device 2170 prompts the user to enter a timefor the data transfer. At 2320, telemetry activation device 2170 promptsthe user to contact conductive structures 2171. In the example of FIG.23, telemetry activation device 2170 prompts the user to grab theconductive joysticks on the device. In response, at 2330, power switch215 is closed to connect power from energy source 211 to implanted RFtelemetry circuit 212. At 2340, RF telemetry circuit 212 is activatedand ready for bi-directional communication with remote device 140 via RFtelemetry link 150. In one example, implanted RF telemetry circuit 212sends a signal to remote device 140. If the signal is received by remotedevice 140, and remote device 140 is available to communicate with animplantable device, remote device 140 sends a responsive signal back toimplanted device 110, and the RF telemetry is established at 2350. Ifthe RF telemetry cannot be established at 2350, because of excessiveenvironmental noise or other reasons, RF telemetry circuit 212 willrepeat 2340 after a delay 2355. In one example, delay 2355 is aprogrammed constant. In another example, delay 2355 is a function of thenumber of failed attempts to establish the RF telemetry. This functionrepresents a particular sequence of successive attempts to establish theRF telemetry. In another example, remote device 140 periodically sends asignal including a digital key identifying a particular implantabledevice 110. Only upon receiving this signal, RF telemetry circuit 212sends out a signal to remote device 140 to establish RF telemetry at2350. At 2360, remote device 140 indicates whether RF telemetry link 150has been established. If so, the user may then remove hands fromconductive structures 1371. At 2370, data is transmitted from remotedevice 140 to implanted device 110 and/or from implanted device 110 toremote device 140. After data communication is complete, the RFtelemetry enters an idle state. Power switch 215 is then opened at 2380to disconnect power from energy source 211 to at least a portion of PFtelemetry circuit 212. Examples of methods and apparatuses controllingthe opening of power switch 215 are described later in this document. At2390, remote device 140 indicates whether the telemetry session wassuccessful, such as by logging or displaying a message.

Example of Power-Off by Sending Command via RF Telemetry

FIG. 24 is a schematic/block diagram illustrating one example ofportions of a telemetry power management system controlling power-off ofat least a portion of the telemetry. In this example, once RF telemetrylink 150 has been established by using one or more of the approachesdiscussed above, a telemetry power-off signal is sent to implanteddevice 110 via RF telemetry link 150. The telemetry power-off signal isan encoded command, such as a unique digital code. In this example,switch controller 214 includes a power-off signal detector 2480 coupledto antenna 213. Upon detection of the power-off signal, detector 2480opens power switch 215 to disconnect the power to at least a portion ofimplanted RF telemetry circuit 212 from energy source 211. In a furtherexample, detector 2480 opens power switch 215 upon detection of thepower-off signal and determination that RF telemetry has entered an idlestate.

FIG. 25 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 24. At 2500, remote device 140sends a power-off signal to implanted device 110 to terminate apreviously-established RF telemetry session. In one example, a physicianor other caregiver provides a user input at a user-interface thattriggers the power-off signal. In another example, remote device 140sends the power-off signal automatically when it determines that an RFtelemetry session should end. For example, remote device 140 determinesthat an RF telemetry session should end when no data is transmitted viaRF telemetry link 150 for a predetermined duration, such as ten minutes.At 2520, implanted device 110 receives the telemetry power-off signal.At 2530, power-off signal detector 2480 determines whether the RFtelemetry is in an idle state, in which no data is being transferredbetween implanted device 110 and remote device 140. In one example, ifdata is being transferred, or is about to be transferred, power-offsignal detector 2480 repeats a step 2530 of determining whether the RFtelemetry is in an idle state after a predetermined delay 2532. At 2540,after the RF telemetry is determined to be in an idle state, implanteddevice 110 sends a termination signal to remote device 140 to informremote device 140 of the completion of the RF telemetry session. Then,at 2550, power switch 215 is opened to disconnect the power to at leasta portion of implanted RF telemetry circuit 212 from energy source 211.Upon receiving the termination signal from implanted device 110, remotedevice 140 indicates a successful completion of the RF telemetry sessionat 2560, such as by logging or displaying a message.

Example of Power-Off by Timing

FIG. 26 is a schematic/block diagram illustrating another example ofportions of a telemetry power management system controlling power-off ofat least a portion of the telemetry. In this example, switch controller214 includes a timer 2682 coupled to implantable RF telemetry circuit212. Timer 2682 starts timing an interval when the RF telemetry entersan idle state. If data transmission via the RF telemetry resumes duringthe predetermined delay, timer 2682 is reset and does not restart untilthe RF telemetry enters another idle state. If the delay expires duringthe idle state, timer 2682 opens power switch 215 to disconnect thepower to at least a portion of implanted RF telemetry circuit 212 fromenergy source 211.

FIG. 27 is a flow chart illustrating one example of a methodcorresponding to the example of FIG. 26. In this example, an idle stateof the RF telemetry, during which no data is transmitted betweenimplanted device 110 and remote device 140, terminates RF telemetrysession at 2700. At 2710, when the RF telemetry enters an idle state,timer 2682 is then started at 2720 to measure a time spent in the idlestate. If data transmission via RF telemetry link 150 resumes at 2730,before the time value exceeds a predetermined delay, timer 2682 is reset(re-zeroed) and is to be restarted upon reentering the idle state. Ifdata transmission via RF telemetry link 150 does not resume before thetime value exceeds the predetermined delay at 2740, implanted device 110then sends a termination signal to remote device 140 to inform remotedevice 140 of the completion of the RF telemetry session. At 2760, powerswitch 215 is opened to disconnect the power to at least a portion ofimplanted RF telemetry circuit 212 from energy source 211. At 2770, ifthe termination signal from implanted device 110 is received, remotedevice 140 indicates a successful completion of the RF telemetrysession, such as by logging or displaying a message.

Example of Power-Off by Using Inductive telemetrv

In one example, once RF telemetry link 150 has been established, aphysician or other caregiver uses the inductive telemetry link 755 ofFIGS. 7 or 8, to end the RF telemetry session. This allows immediateshutoff of RF telemetry link 150 regardless of whether the RF telemetryis in the idle state. An encoded RF telemetry power-off signal is sentfrom external programmer 745 to implanted device 110 through inductivetelemetry link 755. Upon detection of the RF telemetry power-off signal,implanted inductive telemetry circuit opens power switch 215 todisconnect the power to at least a portion of implanted RF telemetrycircuit 212 from energy source 211. FIG. 28 is a flow chart illustratingone example of a method corresponding to this example.

In the example of FIG. 28, at 2800, a physician or other caregiverprovides input to a user interface that causes external programmer 745to terminate a previously-established RF telemetry session. In oneexample, the physician or other caregiver wants to terminate RFtelemetry because a check-up, diagnosis, or treatment session has beencompleted, and the RF telemetry is no longer needed. In another example,physician or other caregiver want to establish RF telemetry with adifferent implanted device. Upon receiving the RF telemetry terminationcommand, external programmer 745 sends the encoded RF telemetrypower-off signal to implanted device 110 at 2810. At 2820, implanteddevice 110 receives the RF telemetry power-off signal. At 2830,implanted device 110 sends a responsive termination signal to remotedevice 140 to inform remote device 140 and external programmer 745 ofthe completion of the RF telemetry session. At 2840, power switch 215 isopened to disconnect the power to at least a portion of implanted RFtelemetry circuit 212 from energy source 211. At 2850, upon receivingthe termination signal, external programmer 745 indicates termination ofthe RF telemetry session. At 2860, if the termination signal fromimplanted device 110 is received, remote device 140 indicates thetermination RF telemetry session, such as by logging or displaying amessage.

Example Choice of Power On/Off Methods

Each power-on or power-off method discussed above offers advantages,which are discussed herein by way as example, and not by way oflimitation. Power-on by RF burst signal allows an RF telemetry sessionto be initiated at remote device 140. This allows a physician or othercaregiver to provide care to a patient from a remote location. Anexamination of the patient may be performed with or without thepatient's knowledge. In one example, the patient's routine check-up isperformed through the RF telemetry and telephone, so that the patientsaves a trip to a physician's office. In another example, the patientwho needs close monitoring is frequently checked by the physician orother caregiver through the RF telemetry, so that the patient need notbe hospitalized to receive similar care. Power-on by physical activityallows an RF telemetry session to be initiated by a patient or a personwith the patient. No additional external device is required. In oneexample, implanted device 110 already includes an accelerometer as anactivity or metabolic need sensor employed in a therapy algorithm. Thesame accelerometer may be used for telemetry power management bymodifying only software. Power-on of RF telemetry using inductivetelemetry is convenient when implanted device 110 includes an inductivetelemetry system. Having external programmer 745 available during an RFtelemetry session also provides an alternative communications modalityif RF telemetry is lost because of RF interference or other reasons.Power-on by magnetic field allows RF telemetry power management using amagnet or a hand-held device. This is likely more convenient to handlethan external programmer 745. In one example, implanted device 110already includes a function activated or suppressed by an externalmagnet. For example, holding a magnet near implanted device 110 maycause it to pace at a fixed pacing rate, overriding any therapyalgorithm that would be otherwise effective. Using a magnetic field forRF telemetry power management in this example may be implemented bymodifying only software. Power-on by introducing a signal via surfaceECG electrodes is convenient when remote device 140 includes an ECGmodule. During a patient's follow-up visit to a physician, the physiciantypically attaches ECG electrodes to the patient to diagnose thepatient's condition. By automatically detecting when the cables fromsuch ECG electrodes are connected to the programmer, telemetry isseamlessly automatically activated without requiring physicianintervention. In another example, using RF telemetry provides for ahigher rate of data transmission as compared with inductive telemetry,reducing the duration of a telemetry session. Power-on by momentarilycontacting an external device allows a patient to initiate and/orschedule an RF telemetry session and is convenient for patients whoregularly use a medical device such as a monitor.

Power-off by sending a command via RF telemetry deactivates implanted RFtelemetry circuit 212 without wasting power by keeping the RF telemetrypower on longer than necessary. However, under some circumstances RFtelemetry link 150 may be interrupted before the power-off signal issent to implanted device 110. Examples of such circumstances include astrong RF noise or a patient moving beyond a range of the RF telemetry.Under such circumstances, power-off using a timer ensures that implantedRF telemetry circuit is shut off after the RF telemetry has been idlefor a predetermined period of time. Power-off using inductive telemetrypermits the physician or other caregiver to immediately terminate the RFtelemetry at any time. In one example, the physician or other caregiverterminates an RF telemetry that is accidentally established with anunintended implantable device. An inductive telemetry is less likely tobe accidentally established because it often requires the wand to beclosely (within a few inches) coupled to the implantable device. Inanother example, the physician or other caregiver may terminate the RFtelemetry by using the inductive telemetry, such as when one or moreother power-off methods fail. In a further example, the one or moreother power-off methods fail because of the presence of a noise, such asa cellular phone signal.

Depending on the patient's needs for care and type of implantabledevice, one or more of the power-on methods and one or more of thepower-off methods discussed above may be included in one implantabledevice. Using more than one method to connect/disconnect power fromenergy source 211 to implanted RF telemetry circuit 212, or at leastportions thereof, increases the reliability of initiating andterminating the RF telemetry session in a timely manner. This ensurespatient safety, conserves energy, and hence increases device longevity.If one method fails, another available method may be automatically ormanually applied. In one example, implanted device 110 employs onepower-on method but several power-off methods, such as all threediscussed above. This decreases energy waste and patient risks byensuring that implanted RF telemetry circuit 212 is deactivated as soonas the RF telemetry session ends.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the implantable devicecan be any implantable medical device having an active electroniccircuit. Many other embodiments will be apparent to those of skill inthe art upon reviewing the above description. The scope of the inventionshould, therefore, be determined with reference to the appended claims,along with the full scope of equivalents to which such claims areentitled. In the appended claims, the terms “including” and “in which”are used as the plain-English equivalents of the respective terms“comprising” and “wherein.”

1-2. (canceled)
 3. A system comprising: an implantable medical device,the implantable medical device including: a far-field radio-frequency(RF) first telemetry circuit: a power connection module, coupled to thefirst telemetry circuit, the power connection module including aconductivity state to connect/disconnect power to at least a portion ofthe first telemetry circuit; and a wireless signal detector including, anear-field inductive second telemetry circuit coupled to the powerconnection module, to control the conductivity state of the powerconnection module upon detecting a predetermined wireless near-fieldinductive signal.
 4. The system of claim 3, in which the secondtelemetry circuit includes a receiver adapted to receive thepredetermined wireless signal, and in which the predetermined wirelesssignal includes a command for changing the conductivity state of thepower connection module.
 5. The system of claim 3, in which the secondtelemetry circuit includes a receiver adapted to detect a near-fieldinductive signal having a predetermined frequency and to change theconductivity state of the power connection module when the near-fieldinductive signal is detected.
 6. The system of claim 3, in which thesecond telemetry circuit includes a receiver adapted to detect anear-field inductive telemetry communication and to change theconductivity state of the power connection module when the near-fieldinductive telemetry communication is detected.
 7. The system of claim 3,further including: a first remote device, electromagnetically coupled tothe first telemetry circuit, the first remote device including afar-field RF third telemetry circuit to provide communication with theimplantable medical device for at least a six-foot range; and a secondremote device, inductively coupled to the second telemetry circuit, thesecond remote device including a near-field inductive fourth telemetrycircuit to provide near-field communication with the implantable medicaldevice.
 8. The system of claim 7, in which the first and second remotedevices are physically integrated.
 9. A system comprising: animplantable medical device, the implantable medical device including: afar-field radio-frequency (RF) first telemetry circuit; a powerconnection module, coupled to the first telemetry circuit, the powerconnection module including a conductivity state to connect/disconnectpower to at least a portion of the first telemetry circuit; and awireless signal detector including a low power radio detector adapted todetect a predetermined telemetry activation signal.
 10. The system ofclaim 9, in which the predetermined telemetry activation signal includesan RF burst and a digital key adapted to identify a particularimplantable medical device.
 11. The system of claim 9, further includinga remote device including a telemetry activation signal generatorconfigured to be electromagnetically coupled to the low power radiodetector.
 12. A system comprising: an implantable medical device, theimplantable medical device including: a far-field radio-frequency (RF)first telemetry circuit; a power connection module, coupled to the firsttelemetry circuit, the power connection module including a conductivitystate to connect/disconnect power to at least a portion of the firsttelemetry circuit; and a wireless signal detector including a magneticfield detector adapted to detect a magnetic field having a magneticfield strength that exceeds a predetermined threshold.
 13. The system ofclaim 12, further including a magnetic field provider separate from theimplantable medical device.
 14. The system of claim 13, in which themagnetic field provider includes at least one of a magnet and a batterypowered portable magnetic field provider.
 15. (canceled)
 16. A systemincluding: an implantable medical device, the implantable medical deviceincluding: a far-field radio-frequency (RF) first telemetry circuit; apower connection module, coupled to the first telemetry circuit, toconnect/disconnect power to at least a portion of the first telemetrycircuit; and an activity sensor, coupled to the power connection module,to control a conductivity state of the power connection module.
 17. Thesystem of claim 16, in which the implantable medical device includes animplantable cardiac rhythm management device, and the first telemetrycircuit provides at least a six-foot telemetry range.
 18. The system ofclaim 16, in which the activity sensor includes an accelerometer. 19.The system of claim 18, further including a pattern recognition module,coupled to the accelerometer, to detect at least one predeterminedpattern of acceleration. 20-22. (canceled)
 23. A system including: animplantable medical device the implantable medical device including: afar-field radio-frequency (RF) first telemetry circuit; a powerconnection module, coupled to the first telemetry circuit, the powerconnection module including a conductivity state to connect/disconnectpower to at least a portion of the first telemetry circuit: a telemetryactivation sensing circuit, coupled to the power connection module, tocontrol the conductivity state of the power connection module upon adetection of a predetermined telemetry activation signal; a cardiacsignal sensing amplifier having an input and output, the output coupledto the telemetry activation sensing circuitry, the telemetry activationsensing circuitry detecting the telemetry activation signal using theoutput of the cardiac signal sensing amplifier.
 24. A system including:an implantable medical device, the implantable medical device including:a far-field radio-frequency (RF) first telemetry circuit; a powerconnection module, coupled to the first telemetry circuit, the powerconnection module including a conductivity state to connect/disconnectpower to at least a portion of the first telemetry circuit; a minuteventilation sensor circuit, including an output coupled to the telemetryactivation sensing circuit; and a telemetry activation sensing circuit,operatively coupled to the power connection module and the minuteventilation sensor circuit, to control the conductivity state of thepower connection module upon a detection of a predetermined telemetryactivation signal based on the output of the minute ventilator sensorcircuit. 25-27. (canceled)
 28. A system including: an implantablemedical device, the implantable medical device including: a far-fieldradio-frequency (RF) first telemetry circuit; a power connection module,coupled to the first telemetry circuit, to connect/disconnect power toat least a portion of the first telemetry circuit; and a timer, coupledto the power connection module, to change a conductivity state of thepower connection module after waiting a predetermined period of timeafter the first telemetry circuit enters a predetermined state thatincludes at least one of a data transmission idle state and a telemetryestablishment failure state.
 29. The system of claim 28, in which theimplantable medical device includes an implantable cardiac rhythmmanagement device, and the first telemetry circuit provides at least asix-foot telemetry range.
 30. A method including: connecting at leastone portion of a far-field radio-frequency (RF) first telemetry circuitin an implantable medical device to an energy source through a powerconnection module; detecting a first predetermined wireless signal;changing a conductivity state of the power connection module when thefirst predetermined wireless signal is detected to couple power to theat least one portion of the first telemetry circuit; detecting a secondpredetermined wireless signal; and changing a conductivity state of thepower connection module to decouple power to the at least one portion ofthe first telemetry circuit when the second predetermined wirelesssignal is detected and the first telemetry circuit enters an idle state.31. The method of claim 30, in which the implantable medical deviceincludes an implantable cardiac rhythm management device, and the firsttelemetry circuit provides at least a six-foot telemetry range.
 32. Themethod of claim 30, in which detecting the predetermined wireless signalincluding detecting a near-field inductive predetermined wirelesssignal.
 33. The method of claim 32, in which the predetermined wirelesssignal includes a magnetic signal having a predetermined frequency. 34.The method of claim 32, in which the predetermined signal includes acode initiating communication activity of the first near-field inductivetelemetry circuit.
 35. The method of claim 32, in which thepredetermined wireless signal includes a command code, the command codeincluding a command for changing the conductivity state of the powerconnection module.
 36. The method of claim 30, in which thepredetermined wireless signal includes an RF burst signal, and changingthe conductivity state of the power connection module includesconnecting power to the at least one portion of the first telemetrycircuit.
 37. The method of claim 30, in which the predetermined wirelesssignal includes a termination code, and changing the conductivity stateof the power connection module includes disconnecting power to the atleast one portion of the first telemetry circuit.
 38. The method ofclaim 30, in which the predetermined wireless signal includes a magneticfield strength signal, and changing the conductivity state of the powerconnection module when the predetermined wireless signal is detectedincludes changing the conductivity state of the power connection modulewhen the strength of the magnetic field exceeds a predeterminedthreshold for at least a predetermined period of time.
 39. A methodincluding: connecting a first far-field radio-frequency (RF) telemetrycircuit in an implantable medical device to an energy source through apower connection module; monitoring an activity level; and changing aconductivity state of the power connection module when the activitylevel exceeds a predetermined threshold.
 40. The method of claim 39, inwhich the implantable medical device includes an implantable cardiacrhythm management device, and the first telemetry circuit provides atleast a six-foot telemetry range.
 41. The method of claim 39, in whichmonitoring the activity level includes monitoring an acceleration. 42.The method of claim 41, in which monitoring the acceleration includesmonitoring a predetermined pattern of the acceleration. 43-47.(canceled)
 48. A method including: connecting at least one portion of afar-field radio-frequency (RF) first telemetry circuit in an implantablemedical device to an energy source through a power connection module;monitoring data transmission activity of the first telemetry circuit;and changing a conductivity state of the power connection module todisconnect power to the at least one portion of the first telemetrycircuit when the first telemetry circuit exists in an idle state for apredetermined period of time.
 49. The method of claim 48, in which theimplantable medical device includes an implantable cardiac rhythmmanagement device, and the first telemetry circuit provides at least asix-foot telemetry range.
 50. A method including: connecting at leastone portion of a far-field radio-frequency (RF) first telemetry circuitin an implantable medical device to an energy source through a powerconnection module; changing a conductivity state of the power connectionmodule to connect power to the at least one portion of the firsttelemetry circuit; attempting to establish communication between thefirst RF telemetry circuit and an external device using the implantablemedical device; and if the attempt to establish communication fails:changing the conductivity state of the power connection module todisconnect power to the at least one portion of the first telemetrycircuit; and repeating the attempt to establish the communication afterwaiting for a predetermined period of time.
 51. The method of claim 50,in which the implantable medical device includes an implantable cardiacrhythm management device, and the first telemetry circuit provides atleast a six-foot telemetry range.
 52. (canceled)
 53. A method including,connecting at least one portion of a far-field radio-frequency (RF)first telemetry circuit in an implantable medical device to an energysource through a power connection module; detecting a predeterminedfirst telemetry activation signal in which the first telemetryactivation signal includes at least one of: a magnetic field presentnear the implantable medical device; and an activity signal; andchanging a conductivity state of the power connection module, when thefirst telemetry activation signal is detected, to connect power to theat least one portion of the first telemetry circuit; detecting apredetermined second telemetry activation signal; and starting datatransmission using the first telemetry circuit when the second telemetryactivation signal is detected. 54-55. (canceled)